Obtaining and analyzing samples of fluid from subsurface reservoir formations is often conducted during oil and gas exploration. Such operations are hindered by the harsh subterranean environment specific to oilfields, including high temperature and pressure (HPHT), corrosive fluids, and severely constrained geometry. The difficulty in acquiring and performing measurements on fluidic samples in such an environment are further complicated by use of electronic sensors that typically require power, monitoring and/or telemetry.
Several oil-field related operations, such as fracturing a geological formation, would greatly benefit from the capability of producing a map of the subterranean fracture geometry, and of the fracture evolution in time. Such capability does not currently exist. A similar need exists for a technology which can be used in monitoring and performing fracture analysis of subterranean carbon dioxide sequestration reservoirs.
Measurements of fluid properties and composition from an oil well are difficult to perform in the oilfield environment. The capability to inject very small sensing devices far into a geological formation by use of a Proppant or similar means of sensor transport, and to be able to determine their position and the precise moment when they perform a measurement or acquire a sample would greatly benefit the industry.
Measurements need to be performed in other types of situations, where the deployment of active sensing systems with on-board electronics and data transmission capabilities may either be impossible due to environmental issues (for example temperatures and pressures that are too high) or may prove to be too expensive to justify economically. Typical examples involve measurements within aquifers, potable water wells, or in a submarine environment. Such an environment may be a lake, or a sea or ocean. Still further environments include where or when there is a lack of power, such as in remote areas of the world.
The capability to perform viscosity measurements on fluid samples is extremely important in a variety of industries: chemical engineering, food industry, oilfield, to name a few. Usually this is accomplished using large laboratory instruments such as capillary viscometers and rheometers, or by using portable lighter weight instruments. In most cases, these instruments are operated using electrical power, and require sample manipulations that are difficult to automate. In some environments such instruments may be impractical due to their size (such as in difficult to reach areas, or within downhole oilfield tools), may be dangerous due to their electrical operation (inside explosive environments such as refinery facilities and tanks, near oil and gas wells), may be incompatible with the shocks or vibrations (within an oil well), or may be simply difficult to adapt. In this case new types of viscosity measurements need to be devised that avoid such inconveniences.
Samples often need to be acquired in explosive atmospheres (ATEX environments) such as inside refinery tanks (to determine the fluid quality and stratification), within refineries or gas plants or other facilities dealing with explosive environments. In such situations the sampling equipment should not pose a risk of generating an explosion, as would be the case if an electrical spark were created. All-mechanical systems that are ATEX-certified are currently used in the industry to perform this type of sampling.
Furthermore, samples may need to be acquired from fluids that are at high pressure, such as in a chemical factory, a refinery, inside an oil well, or at high depth within the ocean. When pressure is lowered, such samples may change (or degrade) by undergoing a thermodynamic phase transition leading to phase separation (i.e. gas may separate from oil, or asphaltenes may precipitate from heavy oil), in a possibly irreversible manner. Sample containers in this case may need to be filled slowly, at controlled inflow into the sample vial or chamber, in order to preserve the thermodynamic equilibrium and prevent, for example, a pressure shock that may lead to phase separation or other irreversible changes in the sample constituency. Such samples may also need to be maintained at high-pressure conditions subsequent to sample acquisition (for example during sample tool retrieval, or during transportation to a remote laboratory), to prevent sample degradation and maintain the sample characteristics unchanged.
Additionally, samples are often required in environments that pose objective risks and dangers, or that are physically remote, or where frequent sampling using manual devices may prove impractical: sites of nuclear disasters, military battlegrounds, biohazard or chemical hazard areas, terrorist attack sites, remote natural resources such as rivers and lakes, coastal waters and other offshore locations, deep water and sub-sea environments. In such cases, robotic equipment may need to be deployed, and the capability to take and analyze such samples may provide important information that cannot be acquired using the on-board in-line sensors present on such equipment. Such equipment may include autonomous or remotely-operated vehicles or robots; remotely-operated underwater vehicles; autonomous underwater vehicles such as buoyancy-driven gliders and wave gliders; airborne or ground drones; other type of robotic equipment.
Samples often need to be acquired and analyzed to detect trace levels of certain contaminants that may be too dilute to enable direct detection. Sample pre-concentration may be required in such cases, by methods such as filtration using mechanical filters, polymeric filters, fiber glass filters, affinity columns, solid phase extraction columns, gas chromatography pre-concentration tubes and columns, or other types of material showing particular affinity for the contaminant, and possibly included in porous or packed form. Particular care needs to be taken when acquiring such samples to prevent scavenging of the sample by, or its adsorption to, the materials of the sampling vial or chamber, or of the transport tubes. The filter material may need to be backflushed, often with a different solution, to remove filter cake buildup and to generate a pre-concentrated sample that may need to be stored into a separate vial or container for transport, storage, or for further manipulation and/or analysis. Alternatively, the filter itself may be retrieved and analyzed, after applying an optional extraction protocol, using laboratory equipment such as gas chromatography, high precision liquid chromatography (HPLC), mass spectroscopy, gamma ray spectroscopy, or other analytical chemistry, biochemical, biological, or nuclear equipment, and possibly after solvent or thermal desorption.
Often there is a need to perform a chemical or biochemical reaction on the acquired sample, by bringing it in contact with a known quantity of chemical or biochemical reagent that will lead to a property change as a consequence of the reaction. The chemical or biochemical reagent may be present as a liquid, solid, powder, gel, gas, emulsion or foam, and it may be attached to, or immobilized on, a solid substrate such as the walls of a vial, a strip of metal, tissue, plastic, paper (as is the case of colorimetric test strips). The reagent may be lyophilized. Often, the (bio)chemical reaction results in color change, which can be detected optically by spectrophotometric absorbance or by colorimetry. Other times direct fluorescence of the sample, or the presence of a fluorescent byproduct, can be detected by fluorescence measurements. Many other properties of the sample may be measured such as (without limitation) optical absorbance, chemiluminescence, color, turbidity, fluorescence intensity, index of refraction, conductivity, density, viscosity. In some cases the usage of a microplate with multiple wells may be necessary to prepare a sample and perform measurements on it.
Certain chemical or biochemical sample preparation protocols may require more complex sample manipulations, such as reaction with a first reagent, waiting for an incubation or reaction time, and then bringing the sample in contact with a second reagent. This sequence may need to be repeated several times.
For pollution monitoring, often samples are not acquired instantaneously but rather over longer periods of time. The rate of sample intake may be proportional to flow velocity in the body of water being sampled. This technique provides “integrated” water samples, which allow in some circumstances to determine the average pollution of the body of water over a period of time, rather than instantaneous pollution.
In certain applications, the moment when a sample needs to be acquired may not be known in advance, so that a pre-programmed sampling sequence may not be appropriate. In this case, individual control of the moment when each sample is performed may be required. For example, samples may need to be acquired in the aftermath of an unforeseen accident, or as directed by an external signal.
In some cases, there may be a need to acquire a larger number of samples than the capabilities of a single sampling device. In this case, multiple sampling devices may need to be used in a “daisy chain configuration”, in such a way that once a device acquires its maximum number of samples, it automatically triggers the next device that will take over the sampling tasks. Using this approach, the total number of samples that can be acquired is not limited by the capabilities of an individual device.
Often there is a need for injecting, or liberating, small particles or small amounts of chemicals at predefined times into a remote environment, or into an environment which is difficult to access. Such small particles or chemicals may be used as tracers, may participate in chemical reactions, or may be used as pharmaceuticals. Exemplary environments where such particles, chemicals, or pharmaceuticals may be injected include without limitation oil and water reservoirs, pre-existing or induced fractures within such reservoirs or within other geological formations, oil, water and/or gas wells, water bodies such as lakes, rivers and oceans, or a human body. It may be desired that such particles or chemicals react in an aggressive way with the fluid present in the remote environment, for example by producing an explosion or producing a rapid release of energy
Monitoring of hazardous waste disposal reservoirs and of adjacent aquifers for contamination mapping and leaching is also a very important domain, where the need for miniaturized and economical sensing solutions is prominent.
Unintended leaks, spills or discharges occur frequently around industrial sites, and may affect environments such as the deep ocean (off-shore environment), a river, a lake, an estuary, the coastal water, or the atmosphere. In the case of an event concerning an unintended discharge, leak, nuclear or chemical spill from an industrial site or other facility, there is an inherent desire within the industry to understand the impacts of that event on the environment. In addition, it would be desirable to be able to gather accurate data concerning the distribution and movement of the pollution over time as it passes through the environment.
There are many factors that may affect the complex interaction of a leak into a marine environment, including ocean currents, wind, waves, thermoclines, buoyancy, pressure, formation of gas hydrates and phase transitions just to name a few. In order to make the best possible predictions using 3 dimensional models (in space) and 4 dimensional models (over time) as an off-shore leak progresses, real data points are required to be entered into the models. Samples taken at different points and different times around the spill area are a valuable method for determining the progression of a spill through the environment. However, technology today is very limited in terms of deployment and ability to acquire a significant number of samples at multiple depth points, at multiple radial points from the source and at multiple points in time. Sample acquisition systems may need to be deployed in a way that is non-intrusive to the normal operations in and around the industrial facility (which may be a drilling rig, an off-shore platform, a ship, a tanker, a pipe etc.), both on the ocean surface and in the subsea. In the early hours and days after an event occurs, resources are normally dedicated to critical tasks other than environmental monitoring or sampling. Additionally, in most cases, the sampling capability is also not located at the industrial site, but more likely on-shore and may take days for the equipment to reach the offshore facility. There is a need for a system that is put in place around an industrial facility as a precautionary measure at an early stage in the project. Furthermore, the position of the system should be accurately determined at the time of installation. Acquired samples and subsea systems also need to be easily retrievable by an ocean vessel at the ocean surface.
In the case that a sampling system is placed in the marine environment for an extended period of time, biofouling and biogrowth tends to develop on the system, including at the sampling intake ports. Similarly, in a deep-water environment near hydrocarbon production facilities, there is a risk of methane hydrate formation. This provides a serious risk of blockage, contamination and/or unrepresentative sampling. Thus the need for a system that is able to not only remain in standby mode ready for deployment, but also be in a protected environment that rejects any biogrowth or methane hydrate from forming during the standby period.
Often there are cases where a sampling unit or an array of sampling units needs to be deployed in a non-static environment, such as when there is a natural ocean current or wave motion due to winds, or other movement within the water column. This movement may, or may not, be in the same direction at all times, may not be predictable, and may cause the sampling unit or string of units to be in a position that is not vertically above the original anchoring point, or vertically below a buoy or similar water-surface mooring point. Consequently, this may cause error in the assumed position data associated with the sampling unit or array.
Currently, sample loading and measurement protocols for microbiological measurements often need to be performed manually, requiring specialized labor and equipment and incurring significant costs. In addition, such measurements require the collection of a representative sample from the environment being monitored (that may be a lake, a river, a pool, a reservoir, a groundwater well, an estuary, coastal water, drinking water, wastewater on any other water source), and transportation to a specialized laboratory where the measurements are performed. This protocol provides a risk of human error in the sampling and/or transportation procedure, leading to an unrepresentative sample being collected, or to sample contamination and/or degradation during transport. There is a need therefore for a device that is capable to perform the sampling and analysis operation in-situ, in a repeatable and reproducible manner, thus bypassing certain human intervention steps that are prone to creating errors.
In certain applications, there is a need for very precisely controlling the moment when each sample is being acquired in a series of sampling operations. These moments may depend of certain external events that cannot be predicted or anticipated at sampler installation, and therefore the sample acquisition moments cannot be pre-programmed in the sampler design.
A sampler may also require a means to actuate the sampling mechanism in a rapid manner upon the receipt of the signal to sample following external trigger activation, such as in the seconds or milliseconds following the receipt of the signal. Furthermore, a sampling device may require means for confirming that a sample was actually acquired, for recording the exact time when each sample was acquired (also known as a timestamp), as well as a certain amount of information corresponding to the sampling process, such as the total duration over which a sample container was filled, the total amount that was sampled etc.
It is important that any timing mechanism used to trigger the acquisition of a fluid sample be accurate, however in certain applications such timing may not prove accurate enough. For example, timing errors in fluidic clocks may occur due to small manufacturing imperfections that may change the overall timing of the sample acquisition. For example, a ten percent relative error in the volume of a timing cavity will result in a ten percent relative error in the timing of that particular sample acquisition. If the overall timing was designed to be ten hours, a ten percent error will introduce a one-hour absolute error in the timing, so the sample may be acquired an hour prior to, or an hour later than the scheduled time.
Such timing errors provided by fluidic clocks may become particularly problematic when a series of samples needs to be acquired in sequence. For example, assume one sample needs to be acquired every hour for a period of twenty four hours. Twenty four sampling devices are deployed at t=0, device numbered n (1<n<24) having a time constant of n hours prior to triggering the acquisition of its corresponding sample. If there is a ten percent error in the fluidic clock of each sampling device, that means that it is likely that the order of the sampling events will be disturbed. For example, the 10th device may acquire its sample at t=11 h, and the 11th device at t=10 h, thus they will be out of order.